Discovered: May 08, 2003
Updated: February 13, 2007 12:01:11 PM
Also Known As: W32/Fizzer@MM [McAfee], Win32.Fizzer [CA], W32/Fizzer-A [Sophos], WORM_FIZZER.A [Trend], Fizzer [F-Secure], Win32/Fizzer.A@mm [RAV], I-Worm.Fizzer [KAV]
Type: Worm
Systems Affected: Windows

The W32.HLLW.Fizzer@mm:

  • Is a mass-mailing worm that sends itself to all the contacts in the Windows Address Book.
  • Contains a backdoor capability that uses mIRC to communicate with a remote attacker.
  • Also contains a keylogger and attempts to spread through the KaZaA file-sharing network.
  • Attempts to terminate the processes of various antivirus programs if they are found to be active.

NOTE: Virus definitions dated May 9, 2003 were posted as LiveUpdate definitions on May 12, 2003 in response to the upgrade.

Antivirus Protection Dates

  • Initial Rapid Release version May 09, 2003
  • Latest Rapid Release version November 16, 2017 revision 050
  • Initial Daily Certified version May 09, 2003
  • Latest Daily Certified version November 17, 2017 revision 001
  • Initial Weekly Certified release date May 09, 2003

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Yana Liu

Discovered: May 08, 2003
Updated: February 13, 2007 12:01:11 PM
Also Known As: W32/Fizzer@MM [McAfee], Win32.Fizzer [CA], W32/Fizzer-A [Sophos], WORM_FIZZER.A [Trend], Fizzer [F-Secure], Win32/Fizzer.A@mm [RAV], I-Worm.Fizzer [KAV]
Type: Worm
Systems Affected: Windows

When W32.HLLW.Fizzer@mm runs, it does the following:

  1. Copies itself as:
    • %Windir%\iservc.exe
    • %Windir%\initbak.dat

      NOTE: %Windir% is a variable. The worm locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to that location.

  2. Creates the following files:
    • %Windir%\ProgOp.exe (15,360 bytes).
    • %Windir%\iservc.dll (7,680 bytes), which is the keylogger component of the worm.
    • %Windir%\, which contains encrypted email addresses that the worm finds on the infected machine.
    • %Windir%\iservc.dat.
    • %Windir%\Uninstall.pky: The worm checks every 30 seconds to see whether a file with this name exists on the infected machine. If the file exists and is not Read Only or a not a directory, the worm will un-install itself from the infected machine.
    • %Windir%\upd.bin.

      NOTE: These files are not viral by themselves. Therefore, Symantec antivirus products do not detect them as such. Manually delete them if W32.HLLW.Fizzer@mm infected your computer.

  3. Adds the value:


    to the registry key:


    so that the worm runs when you start Windows.

  4. Launches iservc.exe as a process upon startup.

  5. Modifies the default value of the registry key:



    @="%Windir%\ProgOp.exe 0 7 '%Windir%\notepad.exe %1''%Windir%\initbak.dat''iservc.exe'

  6. Attempts to end any processes whose names contain one of the following strings:
    • NAV
    • SCAN
    • AVP
    • TASKM
    • VIRUS
    • F-PROT
    • VSHW
    • ANTIV
    • VSS
    • NMAIN

  7. Creates a mutex, called SparkyMutex, to allow only one instance of the worm to run in the system.

  8. Attempts to connect to many IRC servers using many different user names that the worm carries. Then, it waits for the command from the hacker.
    Some IRC servers that the worm attempts to connect to:

  9. Logs all the keystrokes to the encrypted file, %Windir%\iservc.klg.

  10. Determines the location of the KaZaA file download folder to infect the files. The infection routine involves compressing the original (non-executable) file into the resource section of the worm.

    Then, the worm replaces the original file, for example Music.mp3, with a copy of itself as Music.mp3.exe. This copy of the worm contains the original host. Restore the files infected in this way from a known, clean backup copy.

  11. Connects to an AOL Instant Messenger (AIM) chat room as a newly created, random name where the worm waits further instructions from the hacker.

  12. Runs as an HTTP server on port 81.

  13. Uses ports 2018, 2019, 2020, and 2021 for additional backdoor functionality.

  14. Attempts to connect to Geocities sites to obtain updates. At this time none of these sites are available.

  15. Retrieves the email addresses from the Windows Address Book, cookie files, Internet temporary files, and from files in your personal folder. The worm sends itself to all the email addresses it finds. The worm may spoof the sender's name and email address.

    NOTE: For information on email spoofing, read the document, "You receive email indicating that you have sent out a virus, but scanning all files with current virus definitions does not detect anything."

    The email has the following characteristics:

    Subject: The subject line is randomly chosen from a list that the worm carries. It may be one of the following:
    • I thought this was interesting...
    • rather psychedelic...
    • found this on the net, you might like it...
    • discothèque
    • imbrue
    • Damn it feels good to be gangsta.
    • The way I feel - Remy Shand
    • Paradigm Shift
    • WASSUP!
    • Know Thyself
    • Hell
    • I love you
    • Please discard if you don't like or agree with our present leadership...
    • little popup remover
    • B cannot remember
    • Yo, WASSUP, B?
    • an interesting program...
    • You might not appreciate this...
    • I think you might find this amusing...
    • LOL
    • check this out... hehehe
    • question...
    • see you tomorrow.
    • how are you?
    • you need to lose weight.
    • why?
    • kind of simple, but fun nonetheless.
    • check it out.
    • Ist das nicht lustig? ;)
    • Das Wetter ist gut.
    • Gut geschlafen?
    • erstmal unter die dusche ..
    • Og.. :)
    • Wer ist hier das Schaf?
    • Morgen uggi ;))
    • moin uk-world
    • hierzu kann ich nur anmerken das fix nen Bettnässer ist
    • huhu Camper ;))
    • Sandy es freut mich sehr, daß du heut so gut drauf bist ;)
    • da kannst ja gleich einen kuchen auch noch backen ;D
    • ohje ;)
    • hmm sandy und backen ???
    • heidelbeerkuchen ;)
    • jo Camper, das kann ich auch ;)
    • die dich nur anschnautzen kann und sonst nix ;)
    Message: The message body is randomly chosen from a list that the worm carries. It may be one of the following:
    • I sent this program (Sparky) from anonymous places on the net.
    • The way to gain a good reputation is to endeavor to be what you desire to appear.
    • There is only one good, knowledge, and one evil, ignorance.
    • Watchin' the game, having a bud.
    • Did you ever stop to think that viruses are good for the economy? Maybe the primary creators of the world's worst viruses are the companies that make the Anti-Virus software.
    • Today is a good day to die...
    • so, how are you?
    • the attachment is only for you to look at
      you must not show this to anyone...
    • delete this as soon as you look at it...
    • Let me know what you think of this...
    • If you don't like it, just delete it.
    • thought I'd let you know
    • you don't have to if you don't want to.

    Attachment: The attachment name is randomly generated. It has one of the following extensions:
    • .exe
    • .pif
    • .com
    • .scr
Symantec Netprowler
Symantec has released a Security Update 25 for NetProwler 3.5.1, which includes detection for W32.HLLW.Fizzer@mm. Click here for more information.

Symantec Gateway Security
Symantec has released updates for Symantec Gateway Security, via LiveUpdate, to detect W32.HLLW.Fizzer@mm. Symantec Gateway Security users should run LiveUpdate to ensure protection against this threat.

Symantec Intruder Alert 3.6
Symantec has released an Intruder Alert 3.6 policy with detection for W32.HLLW.Fizzer@mm. Click here for more information. An Intruder Alert 3.5/3.6 Integration Policy for NetProwler 3.5xSU 25 is also available. Click here for more information.

Symantec ManHunt
Security Update 1 has been released to provide signatures specific to W32.HLLW.Fizzer@mm. Traffic related to this worm is detected as "Fizzer Worm Propagation".


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Writeup By: Yana Liu

Discovered: May 08, 2003
Updated: February 13, 2007 12:01:11 PM
Also Known As: W32/Fizzer@MM [McAfee], Win32.Fizzer [CA], W32/Fizzer-A [Sophos], WORM_FIZZER.A [Trend], Fizzer [F-Secure], Win32/Fizzer.A@mm [RAV], I-Worm.Fizzer [KAV]
Type: Worm
Systems Affected: Windows

Removal using the W32.HLLW.Fizzer Removal Tool
This is the easiest way to remove this threat. Symantec Security Response has created a W32.HLLW.Fizzer Removal Tool.

Manual Removal
As an alternative to using the removal tool, you can manually remove this threat.

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Update the virus definitions.
  2. Do one of the following:
    • Windows 95/98/Me: Restart the computer in Safe mode.
    • Windows NT/2000/XP: End the Trojan process.
  3. Reverse the changes that were made to the registry.
  4. Run a full system scan and delete all the files detected as W32.HLLW.Fizzer@mm. Manually delete the non-viral files that the worm dropped.
For specific details on each of these steps, read the following instructions.

1. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
    • Running LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
    • Downloading the definitions using the Intelligent Updater. The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).

      The Intelligent Updater virus definitions are available. Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

2. Restarting the computer in Safe mode or ending the Trojan process
    Windows 95/98/Me
    Restart the computer in Safe mode. All the Windows 32-bit operating systems, except for Windows NT, can be restarted in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."

    Windows NT/2000/XP
    To end the Trojan process:
    1. Press Ctrl+Alt+Delete once.
    2. Click Task Manager.
    3. Click the Processes tab.
    4. Double-click the Image Name column header to alphabetically sort the processes.
    5. Scroll through the list and look for iservc.exe.
    6. If you find the file, click it, and then click End Process.
    7. Exit the Task Manager.

3. Reversing the changes made to the registry

CAUTION : Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
    1. Click Start, and then click Run. (The Run dialog box appears.)
    2. Type regedit

      Then click OK. (The Registry Editor opens.)

    3. Navigate to the key:


    4. In the right pane, delete the value:


    5. Navigate to the key:


    6. In the right pane, modify the default value to:

      notepad.exe %1

    7. Exit the Registry Editor.

4. Scanning for and deleting the infected files
    1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
    2. Run a full system scan.
    3. If any files are detected as infected with W32.HLLW.Fizzer@mm, click Delete.
    4. Using Windows Explorer, locate and delete the files:
      • %Windir%\ProgOp.exe
      • %Windir%\iservc.dll
      • %Windir%\
      • %Windir%\iservc.dat
      • %Windir%\Uninstall.pky.
      • %Windir%\Upd.bin

        NOTE: %Windir% is a variable. The worm locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to that location.

Writeup By: Yana Liu